Train dispatching system for railroads



June 1, 1937. N. D. PRESTON TRAIN DISPATCHING SYSTEM FOR RAILROADS Filed March 19, 1929 4 Sheets-Sheet l June 1, 1937. N. D. PRESTON TRAIN DISPATCHING SYSTEM FOR RAILROADS 4 Sheets-Sheet 2 Filed March 19, 1929 June I, 1937. N. D. PRESTON TRAIN DISPATCHING SYSTEM FOR RAILROADS 4 Sheets-Sheet 3 A90 In Filed March 19, 1929 June 1, 1937. N. D. PRESTON TRAIN DISPATCHING SYSTEM FOR RAILROADS Filed March 19, 1929 '4 Sheets-Sheet 4 Patented June 1, 1937 UNETED STATES TRAIN DISPATCHING SYSTEM FOR RAILROADS Neil 1). Preston, Rochester, N. Y., assignor to General Railway Signal Company, Rochester,

Application March 19, 1929, Serial No. 348,336

41 Claims.

This invention relates to dispatching or centralized control systems for handling traflic on railroads, and more particularly to an improved means for communication between the dispatchers office and the various way stations.

In a system of train dispatching, it is necessary to have a communication system between the dispatchers ofiice and the various way stations under his control, so that indications of train 19 movement may be transmitted to the dispatcher, and so that he may control at will the switches and signals at the various points along a stretch of track, subject to automatic control by track circuits.

1.3 This invention relates to such a communication system of the type, which may be termed syn- 'chronous selection, in which momentary message or channel circuits are set up between the dispatchers ofiice and the several way stations in rapid sequence over a line circuit comprising a signal or message wire and a common wire, the. indications or controls being transmitted over these channel circuits in succession by electric energy located either in the dispatchers office .3 or at the way stations.

In accordance with this invention, the channel circuits are set up successively by the operation of two synchronously actuated selecting devices, one serving to select the stations, and the other to the channel circuits for that station; and one characteristic feature of this invention is this scheme or principle of station selection, coupled with channel selection at the individual stations. A further object of the invention is to make the response for control or indication, as between any given station and the dispatchers ofiice, occur more promptly or frequently by taking the time to set up the individual channel circuits only for that station or stations where the chan- -!0 nel circuits are then to be utilized to transmit either a control, in response to a lever operation by the dispatcher for that station, or to transmit an indication of train movement, in response to a change in track circuit conditions at that par- 15 ticular station.

A still further feature of the invention is that the dispatcher may at will restrict the setting up of the chansel circuits to a given selected station, the communication system being during the time of such manual selection localized, so to speak,

to the particular way station selected, information and control to other stations being discontinued for the time being.

Various other characteristic features and ob- 55 jects of the invention will be in part apparent as the description progresses, and in part pointed out hereinafter.

While the idea of means underlying the invention may take various forms, and may be used in various applications of train dispatching to '5 railroads, one specific embodiment has been shown, utilizing certain devices, and showing the system in the form adopted for the dispatching of trains on single track railroads. This specific, embodiment of the invention is by the way of i0 illustration only; and it should be understood that the invention is not limited to the specific means shown and described, nor to the application to single track railroads.

In the accompanying drawings, in which the parts and circuits are shown diagrammatically, more with a view of making it easy to understand the principles of the invention and scheme of operation, rather than the particular structure of the devices preferably employed, Fig. 1 shows '20 the equipment for-thedispatchers office; Fig. 2' shows the equipment for one way station; Fig. 3 shows some of the parts and circuits of Fig. 1 involved in the automatic starting and stopping of the system; and Fig. 4 shows the parts and circuits of Fig. 1 involved in the test for the need for channel circuit selection.

Dispatchers oflice equipment.Considering first the equipment for the dispatchers ofiice, shown in Fig. 1, it is contemplated that the dispatcher will have before him a diagram of the track under his control, with small electric lamps to indicate the presence of trains, and with control levers correlated with the track diagram by position, identified by name or number, or other- Wise arranged so as to facilitate manipulation by the dispatcher. As typical of this arrangement, there is shown in Fig. 1 two passing sidings S and S with lamps L at the ends to indicate the presence of a train on the usual detector track circuit. Two levers are positioned below each end of each siding, only those for the siding S being shown. One of these levers, marked SM, is for the control of the corresponding switch, and is movable up and down to either of the two extreme positions. The other lever, marked TD, is for the control of the Wayside signals at the corresponding end of the siding to select the direction of trafiic, and is also used to hold these signals at stop, or permit them to clear, subject to track circuit control. This lever TD is preferably arranged to be movable to right or left extreme positions, corresponding to the direction of trafiic to be set up, and also to an intermediate or middle position, in which the signals for the corresponding end of the siding are held at stop.

Each of the levers in the dispatchers office is provided with contacts momentarily closed during the movement of the lever from one operated position to another. As shown, a cam or projection 2 is arranged to engage a roller on a spring contact 3 and force it into engagement with a stationary contact (shown as an arrow), as the lever shifts from one position to another,

the lever TD having two such projections, since it has three different operated positions.

These levers also open and close contacts in their operated positions; and as diagrammatically shown, the lever itself carries an insulated contact piece 4 which engages contacts, shown conventionally as arrows. The lever TD has an extra contact arm 5, mechanically connected thereto, and movable into engagement with three contacts as indicated.

The equipment in the dispatchers oifice also includes a station selector SS, comprising a shaft 6 (indicated by dotted lines) which is driven clockwise, in the direction indicated by the arrow, by a spring I, anchored at one end of the shaft 6, and connected at its other end to a gear 8 rotated by a worm 9 through a suitable friction clutch H] by an electric motor M of any suitable type, energized from a suitable source, as the battery II, and provided with a switch I2 for starting and stopping. Other means may of course be used for providing a torque tending to rotate the shaft 6 clockwise.

The rotation of the shaft 6 of the station selector SS is accomplished step-b-y-step by a suitable escapement device, which as shown comprises an escapement wheel 14, with the number of teeth around its periphery corresponding to the number of stations. A pallet l5 cooperates with these teeth to permit the shaft to ad- Vance one-half step when this pallet is attracted by the stepping magnet l6, and the remaining one-half step, when the pallet is returned to its normal position shown by a spring l1, upon deenergization of the stepping magnet I6.

Fastened to the shaft 6 of the station selector SS are. circuit controlling devices. diagrammatically shown as arms 20, 2| and 22 movable over a series of contacts, there being one contact for each station. These contacts are so spaced around the shaft 6 that their respective arms 2B, 21, or 22 are in position to engage one of these contacts each time the shaft is moved one full step by the movement of the pallet if) over and back. Contacts associated with the first station nearest to the dispatchers office .are marked a,

those with the next station I), and so on. Contact arms 28 and 2| engage contacts 3 and t in the initial position of the shaft 6 shown. These arms, of course, are insulated from each other.

0 The shaft 6 also carries a cam 23, arranged to engage a roller carried by a spring contact finger 24, and move this finger to the pos tion shown, when the station selector shaft 6 is in its initial or starting position. When the shaft 6 advances 65 one step, this spring finger 24 is moved to the right and engages its contact.

The tower equipment also includes a group of channel selectors CS, one for each station. The construction of these channel selectors being the 7 same, only one has been fully shown. In the specific form shown, each channel selector CS comprises a shaft 25 carrying arms 26 engaging a series of stationary contacts. It is contemplated that the number of channels for each sta 5 tion, in the application to a single track railroad in the manner herein explained, will be about eight or ten; and accordingly, the channel selector CS for each station is arranged to make one-half of a revolution for each complete cycle.

The shaft 25 of each channel selector CS is actuated step-by-step by a suitable ratchet and pawl device operated by a spring 27 and a magnet 28. On the shaft 25 of each channel selector CS is a cam 29 arranged to engage a roller 30 in the initial or starting position of the selector, so as to shift the spring arms 3| and 32, one to close a circuit, and the other to open a circuit.

It is assumed that each station, for reasons explained hereinafter, will comprise the two ends of a passing siding; but it should be understood that the railroad may be otherwise divided up into stations, both with respect to the equipment in the dispatchers oflice, and with respect to the equipment at one or more points along the track which operates in unison and constitutes a station equipment. a

Associated with each station selector CS is a relay LV, controlled by the contacts 3 momentarily closed upon movement of the levers for that station from any operated position to another, and also a relay TS, conveniently termed the test relay. The relays LV and TS of several channel selectors CS in the dispatchers ofiice control circuits are connnected to three busses, one 35 for a shift relay SH, another 36 for the channel stepping relay CH, and another 31 for the starting relay ST.

Extending from the dispatchers office throughout the length of the railroad equipped are three line wires, one being a common wire CL, another the signal or message wire SGL, another the impulse or stepping line STL. At the dispatchers office and at each selector location along the track, either a complete station, or part of a station, is a quick acting polarized line relay LR in the stepping wire, this relay LR having its contact fingers biased to the neutral position.

Station equipment.-In the embodiment of the invention selected, it is assumed that the dispatching system is applied to a single track railroad; and in Fig. 2 there is shown two passing sidings PS and PS The track switches at the ends of these passing sidings are assumed to be operated by a suitable power switch machine, under the control of the dispatcher, with suitable approach and detector locking protection, in the manner shown and described, for example, in my prior application Ser. No. 199,325, filed June 16, 1927. Each switch machine, shown conventionally and marked SWM, is arranged to be controlled by a dead-beat polar relay SMR. Suitable signals 38, 39, 4i! and 40 are located and controlled in the manner disclosed in my prior application above mentioned, so as to control trafiic into and out of the corresponding end of each siding in both directions These signals are also under the control of the dispatcher, subject to automatic control by the track circuits of the block signal system; and as illustrative of such method of control by the dispatcher, a relay SG of the dead-beat non-biased polarized type is shown for holding these signals at stop or permitting them to clear, and a relay TDR of the same type for selecting the signal to be cleared in accordance with the direction of traffic selected by the dispatcher and the position of the switch. The specific means for the control of the switch machine and the signals is not material to the present invention, andimay be of the form shown in my prior application above mentioned, or as shown and described, for example, in the application of S. N. Wight, Ser. No. 321,185, filed November 22, 1928.

Referring now to the way station selector equipment, it is assumed that a station selector SS SS etc., and a channel selector CS CS etc., will be located at each end of a passing siding, although the two ends together constitute a way station in the sense that term is here used. These selectors are thus located at the ends of the passing sidings, in order to avoid the line wire that would be required to connect the devices at the two ends of the siding to selectors located either at one end only or at an intermediate point. It will be evident, however, that a station selector and a channel selector may be used for as many controls or indications, for one or more locations, as can be conveniently or economically connected to these selectors. The selector equipment at each siding end is the same, and for simplicity only one has been illustrated. The station selector SS diagrammatically shown, comprising a shaft '52 carrying two rotary arms 43 and 44 movable over a series 5 of contacts, and actuated step-by-step by a ratchet and pawl mechanism, having a magnet 55. The channel selector CS comprises a shaft 46, similarly actuated step-by-step by a pawl and ratchet mechanism, having a magnet 41'. On the shaft 46 are arms 43 for engaging a series of contacts. A cam 49 on the shaft opens a contact 50 at the second step of the shaft 46 after starting from its initial position.

The track relay T, connected to the usual de- 35 tector track circuit at the end of each siding, is interconnected with and controls two relays 52 and 53; and the two relays 53 at the two ends of the siding also control a relay 5 in a manner more conveniently explained hereinafter in 40 connection with the description of the operation.

These various relays and other devices, which have been shown for the left hand end of the passing siding PS, are duplicated for the other end of that siding, and also at the ends of all 5 of the other sidings of the territory equipped.

For simiplicity and illustration, only some of the parts of the complete equipment at a siding end have been shown in Fig. 2 for the right hand end of the siding PS and the ends of the other 5 siding PS The various electric connections are more easily explained in connection with a description of the operation.

In the diagrammatic showing of these circuits,

55 the symbol indicates a connection to the one terminal of a suitable battery or other source of current which may be wholly local, and the symbol minus a connection to the other terminal of that battery. Certain of the cir 6O cults include the line wires, and the symbol 0 indicates a connection to the common wire. At each station or control point, two batteries 55 and 55 preferably storage batteries maintained charged over a suitable trickle charge line, are

5 connected at the neutral or mid-point to the common line CL, and provide a source of current for transmitting indications to the dispatchers office of opposite polarities. The same or additional batteries are used to provide our- 70 rent for local circuits which have been shown as terminated at plus and minus Two batteries, or generators, 56 and'55 in the dispatchers omce are similarly connected to the common line CL, and have terminals marked 75 3+ and B, for applying current of opposite polarity to such circuits as include the common wire.

- Operation The parts are shown in the drawings in normal or inactive condition, the system being at rest. The shaft 6 of the station selector SS in the dispatchers oflfice is held by the pallet i5 in its initial position shown. The spring I is wound up by the motor M to the point where the friction clutch l0 slips, and this spring tends to drive the shaft 6 clock-Wise, in the direction indicated by the arrow. The several channel selectors CS in the dispatchers office are in the initial position shown; and similarly the station selectors and channel selectors at the various was stations are intheir initial position.

Starting.Referring to Figs. 1 and 3, the system is set into operation either as a result of movement of some lever, or by a change in the condition of some track circuit, either becoming occupied or unoccupied.

Assume first that, with the system at rest, the dispatcher operates some lever, as for example the lever TD. This movement of the lever TD to a different operated position momentarily closed its contact 3 and energizes the relay LV over wires 60 and 6!. The relay LV, when picked up, is stuck up through its front contact 62 over wire 63 and through the contact 32 of the corresponding channel selector.

The energization of the relay LV closes its front contact 65 and establishes a circuit for en ergizing the starting relay ST which may be traced through from through said front contact 65, wire 66 to the bus 3?, wires 6'! and 68, upper winding of relay ST, to minus The relay ST, when thus picked up, closes its front contacts 69 and 70.

The starting relay ST, when energized, closes its front contact 10 and permits a positive impulse to be applied to the stepping circuit, from the positive terminal of the battery 56, wire H, front contact 72 of the shift relay SH, wire 13, through front contact it of the relay ST, tothe stepping lines STL, through the line relays LR. in series to the common wire CL and back to the battery 56.

The relay SH is normally energized, with the station selector SS in its initial position by a circuit from arm 20, contact 8, wires M and Zil breaks contact s and opens the circuit normally maintaining the shift relay SH energized. When the relay SH drops, current ceases to flow in the stepping circuit, and the contacts of the The 1'30 patchers ofiice makes a one-half step, its arm line relays LR, drop to the open circuit position,

whereupon the'stepping magnet It for' the station selector SS in the dispatchers office is deenergized and the spring I? moves the pallet to complete the first step. Similarly, the de-energization of the stepping magnets 45, allow the springs to move the shafts 42 one step.

The system, when at rest, is automatically set into operation in a similar way by the dropping or picking up of any track relay. To explain this,

assume that the track relay T in Fig. 2, is dropped by the entrance of a train into the corresponding detector track circuit. As this track relay T drops, its back contact 80 closes an energizing circuit for the relay 52, readily traced on the drawings. The make-before-beak contacts 8| of the relay 52, as it is energized, momentarily close a circuit for energizing the relay 53, which is stuck up through its front contact 82, wire 83 and the contact of the channel selector CS With the relay 53 energized, the relay 52 is stuck up through its front contact 84 and the front contact 85 of the relay 53.

The energization of the relay 53 closes its front Contact 85 and connects common over wire 81 to the arm 43 of 'the station selector SS thence over wire 88 to the signal wire SGL, and thence to the contact arm 2| of the station selector in the dispatchers oflice in its initial or starting position (see Fig. 1), on contact if, over wire 89 to the lower winding of the starting relay ST, and then to 13+.

In this way the starting relay ST is energized in the same way as if a lever had been operated,

- with the same results of applying a positive impulse to the stepping line STL to advance the station selector SS at the dispatchers office and the station selectors at all of the stations along the line one step.

Test of need for channel selectiovi.Assuming now that each of the station selectors throughout the system has been advanced one step to the position corresponding to the first station contact a. In this position, a channel circuit, conventionally called the test circuit, is established between the dispatchers oifice and station No. 1. Referring to Figs. 1, 2 and 4, this test circuit may be traced as follows:starting at common (C) through the test relay TS, wire 90, initial contact of the channel selector for station No. 1, arm 26, wire 9|, to contact a on the station selector SS for the station No. 1, arm 2| (now in the first step position) to the signal line SGL, then over this signal line and wire 88 to the arm 03 of the station selector SS at station No. 1 over wire 92 to the channel selector CS for station No. 1, through its initial contact, wire 93 to contact finger 94 of the relay 54. While all of the arms 43 of the station selectors at the different stations are in the first step position, and are also all connected to the signal line, it is only at station No. 1 that the arm 43 is in engagement with an active contact.

In this connection, it should be remembered that in referring to station No. 1, for reasons later to be explained, it is intended to include both ends of the siding PS; and. although there are shown two station selectors SS and SS and two channel selectors for these ends of this siding, these selectors are in a sense a single unit, being operated simultaneously, and having similar connections between the station selectors and the channel selectors. For this reason, the relay 54, governing the test circuit above traced, is arranged to be energized over line wires and common when either of the relays 53 or 53 at the ends of the siding PS is energized and closes its front contact 95, so that the test circuit determines if the track relay at either end of the siding has assumed a new position since the last OS indication was transmitted. In other words, in determining whether or not the channel circuits for station No. 1 shall be set up, the system automatically determines if any lever associated with either end of the siding PS has been operated to a new position, and also if the track relay T at either end of this siding has assumed a new position. It will be evident that, by suitable duplication and interconnection of parts, the occupied or unoccupied condition of other track sections adjacent the ends of the sidings may be communicated to the dispatcher, in the same way as the condition of the short detector track circuits.

If there has been no change in the condition of the track circuits at station No. 1, since the last clearing out operation, hereinafter explained, the relay 54 is in the de-energized condition, and its contact finger 94 is connected to 3+.

This energizes the test relay TS for station No. 1

in the dispatchers oifice over the channel circuits just traced to move its contact finger 95 'to the right.' If there has been a change in track circuit conditions, then the relay 53 is energized, and current of the opposite polarity is supplied to the test relay TS, moving its contact finger 96 to the left.

On the assumption that the system was started into operation by the movement of a lever for station N0. 1, and that there had been no change in track circuit conditions at station No. 1, the finger 96 of thetest relay TS is moved to the right and the finger 91 of the relay LV is raised, whereupon a circuit is established for energizing the channel stepping relay CH as follows:- starting at negative through the relay CH, wires 93 and 99, bus 36-, wires I00 and IOI, front contact S1 of relay LV, wire I02, contact finger 96 of relay TS to the right, wires I03 and I04, contact a. and arm 20 (now in the station No. 1 position) to If it happened that the starting up of the system had been due to a change in track circuit conditions at station No. 1, the contact finger 96 of the test relay TS would assume the left hand position, energizing the relay CH directly and independently of the condition of the relay LV from the bus 30, over wires I00 and I05, and thence as above traced. In either case, whether a lever for station N0. 1 has been operated, or there has been a change in track circuit conditions at station No. 1, the channel stepping relay CH is energized.

Channel circuit seZection.When the relay OH is energized, it closes its front contact I06, and energizes a relay 33 over a circuit including a back contact I07 of a slow acting relay 34. When the relay 33 is energized, the slow acting relay 34 is also energized through the front contact I08 of relay 33. During the time required for the slow acting relay 34 to pick up, a circuit for applying a negative impulse to the stepping line STL is established over wire I09 from (B) to the front contact II!) of relay 33, wire III, through the back contact N2 of the slow acting relay 34, wire II3, through the back contact I2 of the shift relay SH (now down) over wire I3, through the contact 10 of the relay ST (now closed) to the stepping line STL. After the lapse of time required to cause the slow acting relay 34 to raise its contact fingers, the relay 33 (which is quick acting) is de-energized, and this negative impulse is cut off. When the slow acting relay 34 again drops, the relay 33 is again energized, and another negative impulse is sent; and this operation is repeated until the relay CH drops and opens its contact to prevent energization of the relay 33.

The first negative impulse on the stepping line STL shifts the contact fingers of the line relay LR to the left energizing the stepping magnet 28 of the channel selector CS for station No. 1 over wire H8, arm 22, contact a, wire II9, magnet 28, to negative The energization of the magnet 23 retracts the stepping pawl and tensions the spring 2?, so that when this negative impulse ceases and the magnet 28 is deenergized, the spring 2'! drives the shaft 25 of this channel selector one step. During this movement of the ,Shaft'25, the cam 29 releases the spring contact finger 3i to close a stick circuit for the relay CI-I from minus relay CH, wires 98 and H4, front contact H5 of the relay CH, wire H6, contact finger 3|, wires II"! and N34 to the contact a, and over arm to plus It is desirable that this stick circuit should be established before the pick-up circuit for the relay CE is broken at the contacts of the relay TS, which is de-energized as soon as the arm is stepped from its initial position; and hence the cam 29 should be constructed so as to release the spring contact finger 3| quickly upon movement of the shaft 25.

During this movement of the shaft 25 from its initial position, the roller is permitted to move to the right by a recess in the cam 29 far enough to move the spring contact finger 32 to the open position, thereby breaking the stick circuit for the relay LV. As soon as the shaft 25 moves a little further, the roller 38 is forced out of this recess in the cam 23, reclosing the stick circuit for the relay LV at the contact finger 32, but still holding the stick circuit for the relay CH closed at the finger 3L The stick circuit for the relay LV is thus re-established at contact 32, in order that the operation of any lever, associated with station No. 1, during the stepping of the channel selector CS, will cause the relay IN to pick up and stick up.

The negative impulses on the stepping line STL cause the line relays LR at all stations to move their contact finger to the left and step around the channel selector CS for station No. l in the dispatchers office and also the channel selectors CS and CS at the station No. 1 along the track. The other channel selectors in the dispatchers omce and along the track are not operated, because their stepping magnets 28 and t'l are not then connected through the contact arms 22 and 44 to the stepping line STL.

As the channel selectors CS and CS at station No. l, and the corresponding channel selector CS in the dispatchers office, are operated step-by-step, the channel circuits for station No. 1 are set up in sequence, and various controls or indications may be transmitted to or from the dispatchers oilice over these circuits succescircuit is set up from (B) through the lever SM, in the opposite position, over wires I20 and i2I, arm 26 in its second step position, wire 9!, contact a and arm 2i of the station selector SS in the dispatchers office, over the signal line SGL to station No. 1, over wire 88 to the arm 43 of the station selector SS at station No. 1, over wire 92 to the channel selector CS of that station, and thence over arm 48 in its second step position, wire I23 to the dead-beat polar relay SMR, which thus moves its contact I24 to the other position, and causes operation of the switch machine SWM to move the switch to the other position. In a similar way, the channel circuits set up successively may be employed to transmit control for the relays SG and TDR to determine the direction of trafiic and the clearing of signals. 6

As typical of the operation of transmitting an OS indication from a Way station to the dispatchers office, assume that the track relay T for the left hand end of the siding PS dropped after the last operation of the system. As soon as the channel selector CS in the dispatchers office and the channel selector CS at station No. l are stepped to the first step position, an OS channel circuit is set up as follows:- starting at the contact I24 of the relay 52 (which being up is connected to B+ of the battery 54, the other end of which is connected to the common line CL), then over wire I25 to the first step contact of the channel selector CS arm Lit, wire 92, contact a, and arm 43 of station selector SS wire 88, signal line SGL to the dispatchers office, arm 21 and contact a, of the station se-. lector SS, wire 9i, arm 26 of the channel selector CS in its first step position, wire IZt, to the OS relay I21, and thence to the common line CL.

When the OS relay I2? is thus energized with a positive impulse, it shifts its contact I28 to the right, where it stays until this relay is sub sequently energized with an impulse of the opposite polarity. This movement of the contact I28 closes a circuit for lighting the OS lamp L through a resistance I29, and a relay I36. The current through the relay I39 is suflicient to attract its armature I3! but not its armature I32, this being easily obtained by using a great air-gap or bias for the armature I32. When the armature I3I is attracted, current flows through the back contact of the armature I32, wire i33, front contact of armature I3I, through the relay I30 and the lamp L. This circuit does not include the resistance S29 and causes the lamp L to light brightly, so that the dispatcher can readily distinguish that lamp as showing a new OS indication. When the dispatcher has observed this new OS indication, he will manually move the armature I32 closer to the relay Hit by a suitable button or key, so that it will be attracted and held, provided that the contact I28 of the OS relay I2! is still to the right. When the dispatcher thus recognizes the OS indication, the lamp L is energized only through the resistance I29 and is lighted more dimly. When an indication is transmitted that the particular track circuit in question is unoccupied by energizing the 0S relay I21 with current of the opposite polarity to shift its contact I28to the left, all current is cut off from the relay I 30, and its armatures I3l and I32 are both retracted to the normal position, extinguishing the lamp L. If the train had already left'the track section in question, by the time the operator recognized the OS indication and manually shifted the armature I32, the lamp L would at once go out, indicating to the dispatcher that this particular track section was then unoccupied.

With the synchronous type system, such as is involved in the present invention, the OS relay I21 in the dispatchers office is not necessarily operated instantaneously and simultaneously with the movement of a train into and out of the corresponding track section, since the ,OS indication for that track section is not trans- .mitted until the corresponding OS channel circuit is set up, and it may happen that this will occur after the train has actually left the track section. For instance, a short high-speed train may enter the track section andlleave it during the period the channel circuits for some other part of the system are being set up for control or indication. Also, the dispatcher may, as hereinafter explained, have manually limited the selection of channel circuits to some other station, so that even a long slow moving train may enter and leave the track section before the corresponding-OS channel circuit is set up.

It is desirable, however, that the dispatcher have adequate information of train movements, and should be able to determine if a train has passed over a given track section at some time, even though he is not advised of that train movement as soon as it occurs. For these reasons, it is desirable to store up, so to speak, the indication of the operation of any track relay until that indication has been transmitted. It will be noted that the relay 52, when once energized by the dropping of the track relay T, is stuck up so long :as the relay 53 is energized; and since the relay 53 does not drop until the contact 50 is opened by the cam 49 upon movement of the shaft 46 from its first step or OS indication position to the second step position, it is assured that the relay 52 will remain up, supplying positive current to the OS channel circuit to indicate occupancy of the track section in question, until the OS indication has been transmitted, even though the train may actually have left the track section. If the train has left the track section, the relay 52 drops when the relay 53 is tie-energized by the opening of the contact 53 and opens its front contact 85. As the relay 52 drops, its make-before-break contacts BI again close the pick-up circuit for the relay 53, the relay 52 being made sufiiciently slow acting to assure the establishing of the pick-up and stick circuits for the relay 53 during this operation. The relay 53 being thus again energized, further.

operation of the channel selector CS is assured to transmit the indication that the track circuit is not occupied, the relay 52 being now down, so that current of negative polarity is transmitted to the relay I2I.

Thus, if a train should happen to enter and leave a track section, before the corresponding OS channel circuit is set up, the corresponding OS relay I2! is operated, first to light the lamp L, and then to permit the lamp L to be extinguished when the dispatcher recognizes it and manually shifts the armature I32. It will be observed that the relay I30, when once energized, keeps the lamp L lighted, irrespective of the position of the contact of the OS relay I2I. This is necessary in order that an OS indication given after a train had actually left the track section may not escape the attention of the dispatcher, the OS relay I2I being in that case energized positively and negatively in quick succession, and without the relay I30, such temporary lighting of the lamp'L might be overlooked by the dispatcher.

In view of these features of the system, the dispatcher may disregard the lamps on the track diagram for a time, or may focus his attention upon a particular station and limit the selection of channel circuits to that particular station, as hereinafter explained, and. yet upon some subsequent operation of the complete system, the OS lamps for all of the track sections which may in the meantime have become unoccupied will light brightly, so that the dispatcher can readily observe what train movements have occurred. After a dispatcher recognizes each of these new OS indications by operating the armature I32 of the corresponding relay I30, he can tell if that particular track section is still occu pied, since the lamp L will then still remain lighted dimly, or if the train has left that track section, since then the lamp L will go out. In this way, the dispatcher can bring himself up to date, so to speak, with regard to the train movements, that may have occurred while his attention was diverted.

7 If desired, make-beforebreak contacts on the relay I30 may be used to energize a bell circuit, so as to give an audible signal whenever any change in OS indications take place.

Station seleotz'on.-Resuming now, the further steps in the complete operation of the system, following the sending of a sufiicient number of negative impulses over the stepping line STL to step the channel selector CS for station No. l in the dispatchers oflice, and the channel selectors CS and CS at station No. 1 along the track around to the starting position, the projection on the cam 29 engages the roller 30 and moves the contact finger 3I to open the stick circuit for the relay CH. At the same time, the arms 26 and, 48 of the channel selectors in question, being in the initial position, the test channel circuit above traced is again set up; and if any lever associated with station No. 1 has in the meantime been operated so as to energize the relay LV, or if the relay 53 at station No. 1 has been energized due to a change in track circuit conditions, then the relay CH is again energized, in the manner previously explained, and causes the channel. selectors to operate again. This operation of the channel selectors is repeated until all of the controls or OS indications for station No. 1 have been cleared out.

When the channel selection for station No. 1 has thus been completed, the contact 96 of the test relay TS is moved to the right and with the relay LV de-energized, an energizing circuit for the shift relay SH is established from plus arm 20, contact (1., wires I04 and I03, contact 96 of the relay TS to the right, wire I02, back contact 97 of relay LV, wires I36, bus 35, wire I3I, back contact I38 of the relay CH, wires I39 and I5, relay SH to negative The relay SH being energized, a positive impulse from the battery 56 is supplied to the stepping line STL over wire II, front contact I2 of relay SH, wire I3 and contact I0 of relay ST. This causes all of the line relays LR. to shift their contact fingers to the right to energize the stepping magnet I6 of the station selector SS in the dispatchers oflice, and the stepping magnets 45 of the several station selectors along the railroad. When the shaft 6 of the station selector SS in the dispatchers ofilce moves one-half step, in response to the energization of the magnet I6, the arm breaks contact with the contact a, and de-energizes the relay SH, whereupon the positive impulse is cut off, the contacts of the line relays LR assume the de-energized position, and the stepping magnets I6 and '45 are de-energized,

completing the full step of the station selector SS in the dispatchers office, and causing the station selectors along the line to be advanced one step. The contact arms of the several station selectors are now in the second step position, in engagement with the contacts b, corresponding to the second station.

When the station selectors throughout the sys tem have assumed positions corresponding to station No. 2, a test channel circuit for that station is set up in the same way as hereinbefore explained in connection with station No. 1. If any lever associated with station No. 2 has been operated, the relay LV for that station is energized, and this causes energization of the relay CH in the same way as previously explained. Also, if there has been any change in track circuit conditions at station No. 2, since the last operation of setting up and clearing out the channel circuits for that station, then the relay 53 is energized and operates the test relay TS to energize the relay CH, in the same way as previously described.

Thus, if there is some new control or OS indication associated with station No. 2 to be transmitted, the relay OH is energized to cause operation of the channel selectors in the'dispatchers office and at station No. 2 until such controls or indications are cleared out, whereupon the station selectors are operated to select station No. 2.

Automatic stepping of stations-On the other hand, if there is no new control or OS indication to be transmitted for station No. 2, the shift relay SH is at once energized, by movement of the contact 96 of the corresponding test relay TS (not shown) to the right, setting up a circuit similar to the one above pointed out, the corresponding relay LV being down. In other words, if the individual channel circuits for station No. 2 are not required to transmit any new control or indication, then the relay SH is at once energized, and the station selectors are operated to pass on to the next station.

In the foregoing description of the operation, it was assumed that the system was set into operation by the movement of a lever for station No. l, or a change in the track relay for that station; and on this assumption it was explained how the individual channel circuits for station No. 1 were set up. It should be understood that the channel circuits for station No. i would be automatically skipped or hurdled, if the system is set into operation due to some other lever operation or track relay change, in the same way as station-No. 2 may be automatically skipped or hurdled, as just explained.

By reason of this feature of the system, the individual channel circuits for any station are not set up, unless they are actually needed to transmit some control or OS indication. If there is no new control to be transmitted to a station, or no new change in track circuit conditions at that station to be communicated to the dispatchers office, then that station is automatically skipped or hurdled, so to speak; and this automatic hurdling is an important feature of the invention. For one thing, the channel selectors are not operated except when necessary to use them, avoiding unnecessary wear. Furthermore, the maximum time delay between the operation of a lever or track relay, and the response thereto at the station or at the dispatchers oiifice, is greatly reduced, making it feasible to employ a greater total number of channel circuits in the system and still not have too long a time delay in the response to the lever operations or change in track circuit conditions for satisfactory manipulation. The pOssible time delay in the response to a lever or track relay operation, of course, in-

creases as the total number of channel circuits is increased, if each and all of the channel cir. cuits are set up during each cycle; and this condition to some degree limits the extension of a dispatching system of the synchronous type. For example, it is found that fifty channel circuits can bet set up and utilized effectively in about three or four seconds; and on this same basis, if two hundred channel circuits were employed and-all were set up on each operation, the possible delay between the responses to a lever movement or track relay Operation would be in the order of twelve to sixteen seconds. In many instances in handling traflic expeditiously, such a delay is d8 cidedly objectionable, particularly in making a non-stop meet at a passing siding. Studies indie cate that, under normal operating conditions, it is not necessary to set up all of the channel'circuits for the system upon each cycle of operation. Under conditions for handling trains ordinarily encountered, within any given period of a few seconds, it is rare that there would be any lever operation or change in track circuit occupancy to be transmitted for more than about ten per cent of the total number of stations. For instance, with twenty passing sidings, it would be rare that trains would happen to enter or leave track sections at the ends of more than twoof these sidings simultaneously or within a period of a few seconds, so that out of all of the channel circuits for these twenty sidings, only those for these two stations would actually have to be used to transmit a new OS indication during one cycle of operation of the system. For these reasons, the automatic hurdling of channel circuits of the stations, made possible by this invention, affords a great saving in the time required to go over or scan the wholeterritory under the control of the dispatcher, and makes it possible, even with a relative large number of channel circuits, to obtain prompt response to any lever operation or change in track circuit conditions. This saving is particularly prominent in the application of train dispatching to long stretches of single track railroad. This saving in the total time cycle of the system may also be utilized, if desired, so as to take more time for setting up each channel circuit, and so that slower operating selecting devices and relays energized over the channel circuits may be employed, thereby tending to obtain more reliable operationand less disturbance by transitory impulses on the line circuits from lightning and other causes.

The same operations described are repeated until all of the stations have been selected and each station skipped or the individual channel circuits therefore set up. After the last station has been selected, the shaft 5 is stepped to its initial position shown. The contacts a, b, etc. may be spaced equally around the shaft 6 according to the number of stations for the particular installation, or a spacing suitable for a maximum number of stations may be used, and the number of contacts and teeth on the escapement wheel I4 selected to fit the particular installation, the last step bringing the shaft 6 to its initial position after moving a variable number of teeth spaces depending on the number of stations i use out of the possible maximum.

Clearing out the channel circuits-At has al- 7 ready been pointed out how the channel selectors at a given station, when once sent into operation, continue in operation until all controls or OS indications for that station have been cleared out.

In the case of station selection, the same clearing out operation is accomplished by the control of the starting relay ST, so that there is always one complete revolution of the station selectors 7 if any lever has been operated, or the relay 53 at any one of the stations has been energized by the dropping or picking up of its corresponding track relay.

To explain this, assume that the station selector SS in the dispatchers ofiice, having once been set into operation, completes one revolution, bringing the parts back to the normal position shown. The cam 23 shifts the finger 24 to break the stick circuit for the upper winding of the relay ST. At the same time the lower winding of the relay ST is connected to the starting circuit through the arm 2| and contact t in the dis patchers ofiice, and through the arms 43 of the several station selectors along the railroad to the front contacts 86 of the several relays 53. If, during the previous rotation'of the station selectors, any lever is operated to a new position for a station which had been passed in the process of station selection, then the corresponding relay LV would be energized, and would maintain the relay ST energized over the bus 31, irrespective of the interruption of its stick circuit. Similarly, if any relay 53 for any station is energized by the picking up or dropping of its corresponding track relay T, after that station had been passed in the process of station selection then the lower winding of the relay ST is energized over the starting circuit.

Thus, if there is a new control or OS indication which was not transmitted during the preceding cycle of station selection, the relay ST is energized, and another cycle of station selection takes place in the same way as previously explained in connection with starting the system from rest. This cycle of station selection continues until, at the end of the last revolution, there is no relay LV energized to supply current to the upper winding of the relay ST, and there is no relay 53 at any of the stations energized to permit current to flow through the lower winding of the relay ST. When this condition exists, the front contact of the relay ST remains open, and the system stays idle, until some lever is operated, or some track relay changes, to start the system up again. Under average operating conditions, the system'is at rest a large part of the time, depending of course upon the frequency of train movement and the number of track circuits controlling OS indications; and the automatic starting and stopping of the system avoids a great deal of unnecessary wear on the various moving parts.

Manual station seZection.-It frequently happens that the dispatcher, in order to handle traffic to the best advantage, should obtain prompt information of the entrance of trains into certain track section, and should be able to obtain quick response to a lever movement. For example, in making a non-stop meet at a passing siding, it is desirable that the dispatcher should know as soon as possible when one of the trains expected has actually reached the siding, so that he can manipulate his levers to change the switches and signals for the other train. It is also important that the switches and signals should quickly start into operation upon such movement of their controlling levers, so that the trains may be able to proceed without actually stopping.

It usually happens that the dispatcher can readily determine ahead of time the particular siding, or position of the railroad, where it is desirable to obtain prompt OS information and quick response to lever operation, since he knows the time When trains left certain points, and their normal running time, and can thus fix very closely the time and place at which trains are most likely next to show up and necessitate some lever manipulation to change switches or signals.

While the automatic hurdling of the channel circuits at stations, above explained, is very helpful in obtaining more prompt OS information and response to lever operations, it may happen that, at critical times when the dispatcher is working for a non-stop meet, trains may enter or leave track sections at other points along the track, in which the dispatcher is not for the moment interested, yet the channel selection for such OS information is automatically set up and may delay the OS information or operation of the switches or signals at the control point the dispatcher wishes to reach, to such an extent that the non-stop meet is not successful.

In view of these conditions, provision is also made in the systern of this invention so that the dispatcher can restrict the channel circuit selection, by a simple manual manipulation, to a particular station at any time and for as long as he wishes. For example, assume that the dispatcher wishes to restrict the channel selection to station No. 1, being content for the time being to disregard any OSinformation from other stations, and having'no need to transmit a control for the time being to any other station. To manually select station No. 1, the dispatcher closes a switch or key K associated with that station, which closes an energizing circuit for the relay LV for station No. 1 from position wire H0, key K, wires l4l, I42 and 6|, relay LV to negative The energization of the relay LV starts the system into operation, assuming it is not then operating, the same as if a lever for station No. 1 had been moved, As long as the lever relay LV is thus maintained energized by the key K, the channel selectors for station No. 1 operate-continuously, since the relay LV is not de-energized by the opening of its stick circuit at the contact 32 each time the channel selector CS in the dispatchers ofiice completes its cycle; and as long as the relay LV is energized, the relay OH is maintained energized by its pickup circuits. If the system should happen to be in operation at the time the key K for station No. 1 is closed, the unfinished station selection continues until station No. 1 is reached, whereupon the system pauses at this station, so to speak, and rapidly sets up the channel circuits associated with that station. It will be noted that the starting relay ST is maintained energized through its upper winding as long as the relay LV is energized.

The same plan of manual station selection applies to all other stations in the same way. .If the dispatcher operates the key K for some other station, such as station No. 3, for example, with the system at rest, the system will start, the station selectors will step around to station No. 3, and then stop, and the channel circuits for .station No. 3 will be set up repeatedly so long as that key K is kept closed.

Whenever any key K is opened, after having been closed, the system will automatically pass on to the next station as soon as all of the station circuits for the station associated with that key K have been cleared out, in the same way already explained.

By thus manually confining the channel selections to a given station, the dispatcher is able to obtain very prompt OS information and response to lever movement, within such a short period of time, in fact, the dispatcher is able to make non-stop meets, or take care of other special trafiic conditions, as effectively as if the indication and controls were transmitted over separate line circuits and could occur exactly simultaneously.

It can now be seen why it is preferable to consider the two ends of a passing siding as constituting one station, in spite of the fact, that on account of economy in line wire, a selector equip ment is located at each end of the siding, since in making a non-stop meet, the dispatcher should have prompt communication with both ends of a siding. A local way station, in the sense used herein, may likewise include several selector equipments located at different control points, in order that the zone or territory embraced within a station may be adapted to the needs of the dispatcher when making manual station selection. For example, with a track lay out of crossovers, stretches of double track and the like, a considerable portion of the dispatchers handling of trafiic, and two or more selector equipments may constitute that station, the associated parts for the selectors being arranged to operate on one unit, and the levers and OS relays in the dispatchers oilice being connected to one channel selector for that station,

The specific embodiment of the invention shown and described, of course, is susceptible to considerable modification and adaptation to fit varying conditions encountered in practice. Any desired number of stations may be employed within the limits of satisfactory control over a single metallic line circuit. The channel selectors for the difierent stations may have any desired number of contacts to take care of the OS indications and controls required for that station; and these channel selectors may be arranged to take either a half or complete revolution for each operation. Any suitable means may be employed for actuating or controlling the movement of the channel and station selectors step by step in response to impulses of the same or opposite polarity applied to the same or different stepping wires at the dispatchers office. It should be understood that these, and other adaptations or modifications, of the particular structure and arrangement of the parts and circuits shown, do not depart from the invention defined in the claims.

What I claim is:-

1. In a dispatching system for railroads, the combination with a dispatchers ofiice and a plurality of traffic controlling devices located at different stations along the railroad, of a communication system between the dispatchers ofiice and the several stations for permitting selective control of said traffic controlling devices and comprising, a circuit selecting device at each station for selectively establishing circuits for the control of said traffic controlling devices, impulse means in the dispatchers office for operating said circuit selecting devices, a station selecting device at each station operable when in a predetermined condition which predetermined condition is different for the several stations to establish an operating connection between said impulse means and the circuit selecting device of each station one at a time, and automatic means in the dispatchers office for simultaneously operating said station selecting devices at the several stations and thereby render said impulse means effective to operate the circuit selecting device at each of the stations when selected.

2. In a dispatching system for railroads, the combination with a dispatchers office and a plurality of trafiic controlling devices located at each tor" several different stations along the railroad track, of automatically operated selecting means for establishing a communication circuit between the dispatchers ofiice and said stations only one at a time, and selecting means at each station automatically operative from the dispatchers of-' fice in response to a series of impulses over the corresponding communication circuit for selectively establishing circuits to control the operation of the plurality of tramc controlling devices at that station.

3. In a dispatching system for railroads, the combination with a plurality of trafiic controlling devices located at each of several different stations along the railroad track and a dispatchers ofiice, of a plurality of channel circuit selecting means one at each station and a corresponding one in the dispatchers ofiice for each of said stations, means for operating the channel circuit selecting means at each station and the corresponding one in the dispatchers oflice simultaneously and synchronously to establish sequentially a plurality of channel circuits between the dispatchers ofiice and that station for controlling said trafiic controlling devices at that station, and means for rendering said last mentioned means eifective for said stations successlvely only one station at a time.

4. In a communication system between a dispatchers office and a plurality of stations for controlling the operation of trafiic controlling devices at the several stations from the dispatchers office, a signal line circuit connecting the dispatchers oflice and the several stations, synchronously operated channel circuit selecting means one at each station and a corresponding one in the dispatchers oflice for establishing over said signal line circuit sequentially a plurality of channel circuits between the dispatchers ofice and any particular selected one of the stations,

means normally at rest and operable to cause such synchronous operation of said channel circuit selecting devices for said selected station,

and manually operable means for setting saidlast mentioned means into operation and for maintaining such operation until manually released.

5. In a dispatching system of the character described, a dispatchers office, a plurality of stations, traffic controlling devices at said stations, channel circuit selecting means at each station operable to establish sequentially a plurality of channel circuits for the control of the trafiic controlling devices at that station, a plurality of similar channel circuit selecting means in the dispatchers ofiice one for each station, control levers in the dispatchers ofiice associated with each station and connected to said channel circuit selecting means for that station, means automatically operating to establish a communication circuit between the channel circult selecting means at said stations only one at a time and the corresponding channel circuit selecting means in the dispatchers office, said means being normally inactive, and being automatically set into operation upon movement of any one of the levers in the dispatchers ofiice, and means for operating simultaneously the particular two of said channel circuit selecting means then operatively connected by said ing communication circuit.

6. In a dispatching system, a dispatchers ofiice, a plurality of stations having traific controlling devices, selecting means at each station, an impulse device in the dispatchers office for operating said selecting means, control levers in the dispatchers ofiice for governing the corresponding traflic controlling devices, station selecting means in part at the dispatchers oflice and in part at the several stations, governing means for automatically operating said station selecting means intermittently to establish communication circuits between said impulse means and said selecting means at said stations only one at a time, said governing means being operated upon the completion of operation of each selecting device to select the next station, and means for al o operating said governing means independently of the operation of said selecting means if none of the control levers for a corresponding station has been changed to a new position since the last operation of said corresponding selectingmeans, whereby the selecting means at any of said stations is not operated unless some on of the levers associated with that station has been operated to a new position.

'7. In a dispatching system, an indication electric lamp in the dispatchers ofiice, a relay for closing the circuit to light said lamp, and manually operable means governed by said relay for dimming said lamp after it has been initially lighted.

8. In a dispatching system of the character described, a stepping line circuit, selecting means operated step-by-step by impulses on said line circuit, and means for impressing impulses on said line circuit to cause such step-by-step operation of said selecting means comprising interconnected quick and slow-acting relays having their energization controlled by said selecting means, whereby a variable number of im pulses may be applied to the stepping line circuit depending upon the number required to cause a complete cycle of operation of said selecting means.

9-. In a centralized traific control system, in combination, an indication means, and control means for automatically energizing the indication means upon occurrence of the act to be indicated, said control means including a stick relay having a stick circuit and an automatically controlled pick-up circuit, saidindication means being in both the stick circuit and the pick-up circuit, a iii iting means in the pick-up circuit, and a manually controlled contact in the stick circuit.

10. In a centralized trafiic control system, in combination, a stepping means for pulsing a stepping line extending between a control oflice and at least one way station, including, a quick acting relay and a slow acting relay, automatic means for energizing the quick acting relay through an energizing circuit including a back point of the slow acting relay, the slow acting relay having an energizing circuit including a front point of the quick acting relay, and a source of energy connected to the stepping line through front'and back points in series, respectively, of the quick and slow acting relays.

11. In a centralized traffic control system, in combination, a stepping means for pulsing a stepping line, extending between a control office and at least one wavstatiomincluding, a quick correspondacting relay and a slow acting relay, automatic means for energizing the. quick acting relay through an energizing circuit including a back point of the slow acting relay, the slow acting relay having an energizing circuit including a front point of the quick acting relay, a source of energy connected to the stepping line throu .1 front and back points in series, respectively of the quick and slow acting relays, test relays at the control office, one corresponding to each of the way stations, controlling said automatic means, and an energizing circuit for each test relay completed if the need for transmission of an OS indication from the corresponding way station exists.

12. In a train dispatching system for railroads, a dispatchers office, a plurality of way stations, traffic controlling devices at each station, a message line circuit and a stepping line circuit connecting the dispatchers office with the several stations, step-by-step means at each station, and means for rendering said step-by-step means at the several stations effective to impulses on said stepping circuit only one station at a time to govern the traffic controlling devices at that station separately in accordance with the energization of said message line circuit at successive time-spaced intervals marked 01f by said step by-step means, said means being governed by combinations of impulses on said stepping circuit.

13. In a train dispatching system for railroads, a dispatchers oiTlce, a plurality of way stations, a plurality of separately operable traffic controlling devices at each station, a signal circuit and a stepping circuit connecting the dispatchers office with the several stations, control apparatus at each station responsive to the energizations of said signal circuit during a series of time-spaced intervals for governing said trafiic controlling devices at that station, step-by-step means at each station and the dispatchers office operated synchronously over said stepping circuit; and means including said step-by-step means for rendering efiective said control apparatus at the several stations responsive to a series of successive energizations on said signal circuit at said time-spaced intervals, only one station at a time.

14. In a system of the type. described, an indication relay in the dispatchers ofiice controllable from a distant station in accordance with the operated condition of a device at that station to be indicated, an electric lamp having two lighting circuits causing said lamp to give distinctive indications, one of said lighting circuits being established while said relay is in one indication condition, storing means initiated by the operation of said indicating relay to said indicating condition for maintaining said lamp lighted by its other lighting circuit independently of said relay, and manually operable means for rendering said storing means ineffective.

15. In a system of the type described, an indication relay in the dispatchers ofiice controllable from a distant station in accorda ce with the operated condition of a device at th: station to be indicated, an electric lamp having two lighting circuits. causing said lamp to give distinguishable indications, one of said l ghting circuits including a contact of said relay, a storage relay included in said lighting circuit and having normally open contacts for closing the other lighting circuit, and manually operable means associated with said storage relay for breaking said other lighting circuit.

16. In a dispatching system for railroads, the combination with a dispatchers oflice and a distant track circuit, an indication relay in the dispatchers ofiice having contacts closed While said track circuit is occupied, an indication lamp in the dispatchers office having an energizing circuit including said contacts, and manually controllable means for maintaining said lamp lighted independently of said indication relay.

17. In a centralized traffic controlling system for railroads, a control office and a plurality of field stations, a stepping circuit connecting said control ofiice and said field stations,. and stepby-step means at said control oflfice and at each of said field stations operated in synchronism by time spaced impulses on said stepping circuit, said step-by-step means including station selecting means responsive to one polarity and control means responsive to the other polarity of said impulses on said stepping circuit.

18. In a dispatching system of the character described, the combination with a dispatchers ofiice and a plurality of separated way stations, a station selecting circuit connecting the dispatchers ofilce with the several stations, and means at each station responding to the number of impulses applied to said circuit and the polarity of said impulses which are of like or unlike polarities in succession for establishing communication between the dispatchers office and said stations only one at a time.

19. In a dispatching system, a dispatchers office, a plurality of stations located at intervals along the track, step-by-step means at each of said stations 'capable of taking a series of steps, a stepping line circuit and a message line circuit connecting the dispatchers ofiice and the several stations, means operable over said stepping line circuit for selecting said stations one at a time, and rendering said step-by-step means at a selected station responsive to take one step for each impulse on said stepping line circuit, impulsing means at said ofiice for applying a series of impulses on said stepping circuit when a station is selected, and means operable at the selected station for transmitting indications on certain steps of said step-by-step means to the dispatchers office over said message line circuit.

20. In a centralized traflic control system for railroads, a dispatchers office, a plurality of way stations, a selector type communication system for establishing communication between said dispatchers office and said way stations one station at a time, a group of control levers in the dispatchers ofiice for each field station, a lever storing relay corresponding to each of said groups of levers for initiating said system to select the station corresponding to that group, a pick-up circuit for each of said lever storing relays momentarily closed upon the movement of any lever of the corresponding group to a new position, and a stick circuit for each of said lever storing relays closed until the corresponding station has been selected.

21. In a centralized trafiic control system for railroads, the combination with a plurality of way stations of a control office, a line circuit connecting said control ofiice with said way stations, a plurality of control levers divided into groups corresponding to the stations, and means for selectively rendering said groups of control levers effective one group at a time to determine the character of a plurality of impulses placed on said line circuit, said means including a storing relay, a pick-up circuit for each of said storing relays momentarily closed whenever a control lever of a corresponding group is moved to a. new position, and a stick circuit for each of said storing relays closed only until its corresponding group of control levers have determined the character of a plurality of impulses placed on said line circuit, and means at said Way stations reresponsive to said series of impulses .placed upon said line circuit.

22. In a dispatching system for railroads, a dispatchers ofiice, a plurality of way stations, a stepping circuit and a message circuit connecting said dispatchers ofiice with said Way stations, step-by-step means at the dispatchers office and at each way station operated synchronously by impulses on said stepping circuit, devices at each static-n having different conditions to indicate in the dispatchers office, a change relay at each way station energized whenever a change occurs in the condition of one of said devices, means initiated when said change relay is energized to cause impulses to be placed on said stepping circuit, means including said step-by-step means and said message circuit for registering in the dispatchers office a changed condition and the particular station at which such changed condition occurred, and a stick circuit for each of said change relays closed until after its corresponding station has been registered in the dispatchers ofiice.

23. In a dispatching system for railroads, a dispatchers office, a plurality of way stations, a stepping circuit and a message circuit connecting said dispatchers ofiice with said way stations, step-by-step means at the dispatchers office and at each way station operated synchronously by impulses on said stepping circuit whereby said system is operable through a cycle of operation including station selecting steps and indication transmitting steps, and means impressing impulses of distinctive characters on said message wire during said station selecting steps for registering a selected station in the dispatchers oflice, whereby the selected station is permitted to impress impulses of distinctive characters on said message Wire during said indication transmitting steps for the transmission of indications from that station.

24. In a centralized traffic control system for railroads, a selective communication system, a trafiic controlling device, a change relay storing a change in the condition of said traiiic controlling device, a condition storing relay conditioned by said traffic controlling device and remaining conditioned until said selective communication system has been effectively operated to transmit indications of said device, means cancelling said change storing relay and said condition storing relay when said communication system is conditioned to transmit, and a pick-up circuit for said change storing relay including make-beforebreak contacts of said condition storing relay and. closed momentarily upon the cancelling of said condition storing relay.

25. In combination, a central o-ffice, a plurality of field stations, a normally-at-rest selector type communication system connecting said control office and said field stations, a traflic controlling device at each field station, a control lever in said ofiice for each trafiic controlling device, a stick relay for each lever having a pickup circuit completed momentarily during movement of its associated lever from one active to another active position, a circuit including an active contact of a lever controlled by the associated stick relay for transmitting through the medium of said communicating system a control corresponding to the position then assumed by such lever to the corresponding traffic controllingdevice at the field station, and means for initiating said communication system from rest controllable independently by a front contact of each of said stick relays.

26. In a selector type system for controlling railway tramc controlling devices and which is normally at rest; the combination with a plurality of field stations, each having a plurality of trafiic controlling devices, and a central oflice; of a lever in said ofiice for each or" said trafiic controlling devices, a stick relay in said ofiice for each way station and having a pick-up circuit closed during the movement of any lever for controlling a trafiic controlling device at such way station from a position to close one active contact to a position to close another active contact, a circuit for transmitting a control to a particular traffic controlling device at a particular way station from its control lever including an active contact of such lever and controlled by the stick relay for that particular way station, and means for initiating said selector system controlled independently by front contacts of all of said stick relays.

27. In a selector type system for controlling railway traific controlling devices and which is normally at rest; the combination with a plurality of field stations, .each having a plurality of traific controlling devices, and a central oifice; of a lever in said office for each of said traffic controlling devices, a stick relay in said ofiice for each way station and having a pick-up circuit closed during the movement of any lever for controlling a traffic controlling device at such way station from a position to close one active contact to a position to close another active contact, a circuit for transmitting a control to a particular traffic controlling device at a particular way station from its control lever including an active contact of such lever and controlled by the stick relay for that particular way station, means for initiating said selector system controlled independently by front contacts of all of said stick relays, and a stick circuit for each stick relay broken when all of the controls for the way station of such stick relay have been transmitted.

28. A selector type system for controlling traffic controlling devices on a railway system including a central office and a plurality of way stations comprising, station selecting apparatus including stepping means at each way station, individual apparatus selecting means at each way station including stepping means efiective only if such way station has been selected, and means at said central office for transmitting a distinctive series of positive and negative impulses arranged in a particular code pattern which series will select a particular way station and will operate the apparatus selecting stepping means at such selected way station only.

19. A selector type system for controlling traffic controlling devices on a railway comprising, a central ofiice, a way station located at a traffic controlling point along the trackway, a coding circuit connecting said oiiice and way station, stepping means for intermittently closing said coding circuit to apply impulses to said circuit, and a code character determining means which if in one position allows the application of code impulses of one character and if in another position allows the application of code impulses of difierent polarity by said stepping means, said code character determining means remaining unchanged during the application of a plurality of like successive impulses.

30. A selector type system for controlling traffic controlling devices on a railway comprising, a central office, a way station located at a traffic controlling point along the trackway, a coding circuit connecting said office and way station, stepping means for intermittently closing said coding circuit to apply impulses to said circuit, and a code character determining means which if in one condition allows the application of code impulses of one polarity and if in another condition allows the application of code impulses of a different polarity by said stepping means, said code character determining means remaining unchanged during the application of a pinrality of like successive impulses.

31. In a selector type control and indication system for railroads, the combination with a central office and a plurality of way stations; of selector apparatus including a line circuit connecting a central office and a plurality of way stations and including station selecting and apparatus selecting stepping means at said central omce and at each way station and normally at rest; impulse creating means at said central oflice tocause said station selecting stepping means to select a particular station and then operate the apparatus selecting stepping means at such station, and means controlled by traific conditions at a particular way station for causing said impulse creating means to create and apply to said circuit the proper code of distinctive impulses to cause said station selecting stepping means to select that way station and then cause the apparatus selecting stepping means at such way station to operate.

32. In a selector type control and indication system for railroads, the combination with a central ofiice and a plurality of way stations; of selector apparatus including a line circuit connecting a central oflice and a plurality of way stations and including station selecting and apparatus selecting stepping means at said central ofiice and at each way station and normally at rest; impulse creating means at said central office to cause said station selecting stepping means to select a particular station and then operate the apparatus selecting stepping means at such station, means controlled by traflic conditions at a particular way station for causing said impulse creating means to create and apply to said circuit the proper code of distinctive impulses to cause said station selecting stepping means to select that way station and then cause the apparatus selecting stepping means at such way station to operate, manually controlled means for each way station at said central ofiice, and means effective upon movement of one of said manually controlled means for causing said impulse creating means to create and apply to said circuit the proper code of distinctive impulses to cause said station selecting stepping means to select the way station with which said manually controlled means is associated and then cause the apparatus selecting stepping means at such way station to operate.

33. In a selector type system for controlling and receiving indications from traffic controlling devices on railroads, the combination with a central office and a plurality of way stations, of normally at rest selector apparatus for transmitting controls and receiving indications including stepping means at said central oflice and at each of said Way stations and connected by an impulsing circuit; and automatic initiating means including a traflic controlled contact at each Way station for causing a distinctive code of impulses to be created at said central office and applied to said circuit to cause the stepping means to be operated only at the oflice and at that Way station.

34. In a selector type system for controlling and receiving indications from traffic controlling devices on railroads, the combination with a central oflice and a plurality of way stations, of normally at rest selector apparatus for transmitting controls and receiving indications including stepping means at said central ofiice and at each of said way stations and connected by an impulsing circuit; and initiating means including a trafiic controlled contact at each way station for causing a distinctive code of impulses to be created at said central oflice and applied to said circuit to cause the stepping means at that way station only to be operated, said initiating means being constructed to render certain way stations superior to others to the use of said selector apparatus if traffic controlled contacts at a plurality of way stations are effective at the same time, such superiority being dependent on the manner in which such apparatus is interconnected and not on the order in which the way stations are located on said impulsing circuit.

35. In a selector type system for controlling and receiving indications from traffic controlling devices on railroads, the combination With a central ofiice and a plurality of way stations, of normally at rest selector apparatus for transmitting controls and receiving indications including stepping means at said central ofiice and at each of said Way stations and connected by an impulsing circuit; initiating means including a traific controlled contact at each way station for causing a, distinctive code of impulses to be created at said central office and applied to said circuit to cause the stepping means at that way station only to be operated to transmit indications to said central ofiice, and manually operable means for each way station at said central office which ii. operated causes the stepping means at such way station to be operated to recheck such indications.

36. In a centralized trafl'lc control system for railroads, the combination with an oifice and a plurality of stations, a track circuit at each of said stations, selector apparatus at said oifice and at each of said stations adapted to successively indicate the condition of each of said track circuits in a s ngle operating cycle, means controlled by said apparatus to cause it to pause at a particular point in said cycle in the event that a particular track circuit is occupied to thereby indicate the occupied condition of said track circuit, and means responsive to a change in conditicn of any of said track circuits to initiate the operation of said apparatus.

3'7. In a dispatching system of the character described, a dispatchers office, a plurality of stations, a plurality of traffic controlling devices at each station, selecting means at each station operable to take a plurality of steps to establish circuits for the control of the corresponding traffic controlling devices at that station, one for each step, impulse means in the dispatchers ofiice for operating said selecting means when rendered efiective, and automatic station selecting means for rendering effective said impulse means and said selecting means at said stations only one station at a time and sequentially during each operating cycle.

38. In a dispatching system of the character described, a dispatchers office, a plurality of stations along the railroad track, a stepping line circuit and a message line circuit connecting said dispatchers oflice with said stations, traffic controlling devices at each of said stations, station selecting means and channel circuit selecting means at each station, station selecting means in the dispatchers ofiice and also a plurality of channel circuit selecting means one for each station, means for automatically operating said station selecting means in the dispatchers office and at the stations over said stepping line circuit to establish communication sequentially between the channel circuit selecting means at said stations one at a time and the corresponding channel circuit selecting means in the dispatchers ofiice over said message line circuit, and means for operating the corresponding channel circuit selecting means in the dispatchers oifice and at a selected station synchronously over said stepping line circuit to establish a series of channel circuits including said message line circuit for respectively controlling said trafiic controlling devices at that station.

39. In a system for dispatching traffic on railroads, the combination with a dispatchers office and a plurality of stations, control levers in the dispatchers office associated with each station, step-by-step selecting means at each station operable to selectively establish a plurality of circuits for the individual control of all traffic controlling devices at that station by their respective levers, impulse means in the dispatchers office for causing the step-by-step operation of said selecting means at said stations, registering means for each station for registering the changed conditions of the control levers for that station irrespective of the number of said control levers which are changed simultaneously, and automatic means for rendering said impulse means effective to cause operation of the selecting means for any particular station only if said registering means associated with that station has registered a change since the last operation of said corresponding selecting means.

40. In a communication system for train dispatching, a dispatchers oflice, a plurality of stations, a plurality of traffic controlling devices at each station, a stepping circuit connecting said dispatchers office with the several stations, control levers in the dispatchers office for each of said traflic controlling devices, step-by-step means at each station, step-by-step means at the dispatchers ofiice for each station, automatic means operating over said stepping circuit for establishing operative connection between the corresponding step-bystep means at said ofiice and at said stations only one station at a time, whereby controls may be transmitted, and manually conditioned means automatically efiective and including said stepping circuit, for causing operation of the step-by-step means for any station to transmit controls between said levers for that station and their respective traific controlling devices only if some one of the control levers for that station has been changed to a new position since the last operation of said selecting means for that station.

41. In a system of the type described, an indication relay in the dispatchers ofilce controllable from a distant station in accordance with the operated condition of a device at that station to be indicated, an electric lamp having two lighting circuits causing said lamp to give distinguishable indications, one of said lighting circuits including a contact of said relay, a storage relay included in said lighting circuit and having normally open contacts for closing the other lighting circuit, and manually operable means governing said storage relay for breaking said other lighting circuit.

NEIL D. PRESTON. 

